// 定义函数 - 用于创建XMLHTTPRequest对象
(function(){
	function createXMLHttpRequest(){
		var httpRequest;
		if (window.XMLHttpRequest){
			HttpRequest = new XMLHttpRequest();
		}else if (window.ActiveXObject){
			try{
				httpRequest = new ActiveXObject("Msxml2.XMLHTTP");
			}catch(e){
				try{
					httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
				}catch(e){}
			}
		}
		return httpRequest;
	}
	window.createXMLHttpRequest = createXMLHttpRequest;
})();